Elastomeric (e.g., rubber, urethane, etc.) bushings are employed in vehicle leaf-spring suspension systems in securing the leaf springs to the vehicle. Bushings dampen vibration transfer between the leaf springs and the vehicle, reduce transmitted road shock, etc.
With reference to FIG. 1, conventional bushings typically comprise two elastomeric cylinders 5a, 5b of generally identical construction, arranged in opposition in the eye of a leaf-spring 10 and secured to a shackle 15 with a shackle bolt 20. Each half of the bushing includes a terminal portion 6a, 6b in the form of a disk of greater diameter than the cylindrical portions. These terminal portions 6a, 6b are captured between the eye of the leaf-spring 10 and the shackle 15, as shown in FIG. 1, and serve to limit the side-to-side travel of the leaf-spring 10 relative to the longitudinal axis of the shackle bolt 20. Unfortunately, contact between the elastomeric material of the terminal portions 6a, 6b and the metal of the shackle 15 creates unwanted noise. To reduce the occurrence of such noise, grease (not depicted) may be applied to the surface of the terminal portions 6a, 6b. However, this grease tends to be washed away rather quickly in vehicle applications, where the bushings are exposed to the elements.